@misc{oai:repo.qst.go.jp:00079432,
 author = {Asakura, Nobuyuki and Asakura, Nobuyuki},
 month = {Sep},
 note = {Conventional divertor concepts for recent DEMOs (P_fus=1.5-2GW, R_p=7-9m) were summarized. Requirements of fradmain and the plasma performance will determine divertor design concept. Approaches of two concepts, i.e. increasing f_rad^main (for ITER-level P_sep/R) and f_rad^div (for larger P_sep/R ~30MWm), will contribute to optimize future DEMO and power plant designs. Power exhaust simulations for DEMO divertor suggested that the total radiation fraction (f_rad = P_rad/P_heat >0.8) is required to reduce both peak-q_target and T_e,i. 
Improvements of lamda_q and detachment models are required. Outer leg length is similar: L_div=1.6-1.7 m and Width of q_// profile is lamda_q =2-3mm. Geometry effects (ITER like closer baffle or without baffle) on plasma detachment profile and the required radiation will be important key to operate the divertor in the low n_e^sep range. 
ITER-like target (W-PFC and Cu-alloy heat sink) is a common baseline design: for a year long operation, Re-Crystallization and Net-Erosion on W, and mechanical property of CuCrZr heat sink under n-irradiation will be anticipated. Restrictions of q_target , T_e,i and T_surface. Integrated design of divertor target, cassette and coolant pipe routing has been developed: two routes for W-PFC&Cu-alloy heat sink (lower-T) and RAFM steel heat sink for baffle/cassette (higher-T). Coolant-T (130-200C) and Cu-alloy property under n-irradiation are design issues. Water-cooled target components (incl. joint/inter layer) for high n-irradiation should be developed., 14th International Symposium on Fusion Nuclear Technology},
 title = {Recent Developments of Plasma Exhaust and Divertor Design for Tokamak DEMO Reactors},
 year = {2019}
}